BTS remains open except for the Office of Airline Information, which is closed and not accepting data submissions due to an appropriations lapse.All BTS releases, except the Transportation Services Index, will be delayed.

c 1960-65, Motorcycle data are included in Light duty vehicle, short wheel base (formerly Passenger car), and Long duty vehicle, long wheel base (formerly Other 2-axle 4-tire vehicle) data are included in Single-unit 2-axle 6-tire or moreTruck.

d In July 1997, the FHWA published revised vehicle-miles data for the highway modes for many years. The major change reflected the reassignment of some vehicles from the Passenger cars category to the Other 2-axle 4-tirevehicles category. This category was calculated prior to rounding.